PRODUCTION OF BASE MATERIAL FOR OPTICAL FIBER

摘要

PURPOSE:To efficiently provide the optical fiber base material which has the excellent adhesion of a core material and a molded article is sufficiently corrected in eccentricity of the molded article to a core material and is less fluctuated in the fiber diameter during drawing by mounting the core material into a forming mold, packing quartz powder therein, press forming this powder to form the molded article on the outer periphery of the core material as a porous base material and cutting the outer periphery thereof to correct eccentricity, then refining and vitrifying the base material to transparent glass. CONSTITUTION:A quartz glass rod 13 is inserted into the rod insertion hole of a lower cap 12 of the forming rubber mold 11 made of urethane. This glass rod 13a is produced by a VAD method and rods 13b for supporting are connected to both ends thereof. Three rotation preventive bodies 14 are previously mounted thereto by glass welding. Granulated particles 10 consisting of silica powder and PVA and having about 150mum average grain size are packed into the cavity in the forming rubber mold 11 while the lower cap 12 is kept vibrated. An upper cap 15 is then mounted to the mold and the mold is installed in a pressurizing device 16. Water is charged into this pressurizing device to pressurize the mold. The molded article is thereafter cut, refined and vitrified to the transparent glass.